1. Field of the Invention
The present invention relates to an improved process for lubricating textile yarns, especially sewing threads, by means of organosilicon polymers which comprise impregnating the threads in an aqueous bath.
2. Description of the Prior Art
It is known to treat sewing threads with organosilicon polymers with the purpose of eliminating or reducing the abrading which is encountered on high speed sewing machines. Various different methods are used to effect this treatment. Among these are the following: applying an oily substance by means of a roller, pulverization (whereby organosilicon polymers which are projected onto the thread are used in pure or in diluted form) immersion into a bath which contains water and/or organic solvents as a diluent.
For the manufacturers or users of textile threads who possess a dyeing apparatus, it is very practical to carry out this treatment by circulating an aqueous bath liquid in this dyeing apparatus.
The working method which is used is analogous to that which is used in a dyeing procedure:
An aqueous dispersion of the organosilicon polymers which is brought to an appropriate temperature, usually in the range of from about 60.degree. to 80.degree. C., and is adjusted to an appropriate pH value, usually in the range of from about 6 to 7.5, is injected into the dyeing apparatus wherein the threads are kept in the form of bobbins which are still soaked in the rinsing water. The dispersions are alternatingly injected either in the direction from the internal zone within the bobbins to the zone outside the bobbins or in the opposite direction. This circulation of the liquid of the dispersion is continued for such a period of time as is needed for depositing the organosilicon polymers on the thread. Subsequently, the bobbins are dried.
Such a treatment is designated as being substantive and is characterized by exhaustive extraction of the major portion of the organosilicon polymer which is introduced in the aqueous dispersion. This technique has evident advantages as compared with the older techniques, such as applying an oil by means of a roller. In the latter case, it is necessary at the end of the dyeing phase, to dry the thread on the bobbins, unspool it and re-spool it after applying the oil.
In the substantive treatment, these necessities are eliminated. However, further improvements of this method are still needed in the art, since carrying out this working procedure requires a very strict adjustment of the pH value and the heating of the dispersions. Furthermore, hardly more than 80 to 90% of the amount of organosilicon polymers which are present in the dispersions are used up. Finally, the polymers are not always deposited homogenously throughout the mass of bobbins.
Instead of effecting the lubrication of the thread by a substantive treatment in a dyeing apparatus after the dyeing operation, it is possible to effect this treatment at the same time as the dyeing by incorporating the organosilicon polymers into the dye bath which contains the dyestuff, as has been disclosed in the French published Patent application No. 2,076,039. However, this process cannot generally be used for all types of dyes, since due to their strongly hydrophobic properties, the organosilicon polymers not only disturb the stability of the dye baths, but also the fixing of the dye on the thread.